Fix warnings in io/ascii_io.cpp
Fix warnings in io/ascii_io.cpp

> ascii_io.cpp:109:21: warning: comparison of integers of different signs: 'int' and 'size_type' (aka 'unsigned long') [-Wsign-compare]
> ascii_io.cpp:165:24: warning: comparison of integers of different signs: 'int' and 'size_type' (aka 'unsigned long') [-Wsign-compare]

shivmalhotra/pcl,v4hn/pcl,mikhail-matrosov/pcl,fskuka/pcl,DaikiMaekawa/pcl,pkuhto/pcl,MMiknis/pcl,v4hn/pcl,cascheberg/pcl,3dtof/pcl,LZRS/pcl,closerbibi/pcl,stefanbuettner/pcl,drmateo/pcl,chenxingzhe/pcl,MMiknis/pcl,srbhprajapati/pcl,the-glu/pcl,DaikiMaekawa/pcl,srbhprajapati/pcl,wgapl/pcl,soulsheng/pcl,locnx1984/pcl,3dtof/pcl,DaikiMaekawa/pcl,fanxiaochen/mypcltest,fskuka/pcl,damienjadeduff/pcl,stfuchs/pcl,krips89/pcl_newfeatures,closerbibi/pcl,chenxingzhe/pcl,raydtang/pcl,drmateo/pcl,simonleonard/pcl,the-glu/pcl,fanxiaochen/mypcltest,locnx1984/pcl,raydtang/pcl,Tabjones/pcl,chatchavan/pcl,cascheberg/pcl,ResByte/pcl,RufaelDev/pcc-mp3dg,shivmalhotra/pcl,jakobwilm/pcl,LZRS/pcl,KevenRing/vlp,raydtang/pcl,starius/pcl,DaikiMaekawa/pcl,closerbibi/pcl,kanster/pcl,KevenRing/vlp,v4hn/pcl,locnx1984/pcl,drmateo/pcl,kanster/pcl,zavataafnan/pcl-truck,damienjadeduff/pcl,KevenRing/pcl,nikste/pcl,jakobwilm/pcl,fanxiaochen/mypcltest,raydtang/pcl,Tabjones/pcl,mikhail-matrosov/pcl,sbec/pcl,nikste/pcl,jakobwilm/pcl,soulsheng/pcl,RufaelDev/pcc-mp3dg,shyamalschandra/pcl,ResByte/pcl,stefanbuettner/pcl,jakobwilm/pcl,RufaelDev/pcc-mp3dg,lebronzhang/pcl,LZRS/pcl,MMiknis/pcl,zhangxaochen/pcl,the-glu/pcl,shyamalschandra/pcl,lebronzhang/pcl,pkuhto/pcl,MMiknis/pcl,lydhr/pcl,LZRS/pcl,kanster/pcl,lebronzhang/pcl,simonleonard/pcl,fanxiaochen/mypcltest,fskuka/pcl,nikste/pcl,shangwuhencc/pcl,DaikiMaekawa/pcl,RufaelDev/pcc-mp3dg,sbec/pcl,sbec/pcl,jeppewalther/kinfu_segmentation,ResByte/pcl,srbhprajapati/pcl,nh2/pcl,msalvato/pcl_kinfu_highres,mschoeler/pcl,simonleonard/pcl,zavataafnan/pcl-truck,starius/pcl,wgapl/pcl,RufaelDev/pcc-mp3dg,damienjadeduff/pcl,the-glu/pcl,msalvato/pcl_kinfu_highres,jeppewalther/kinfu_segmentation,Tabjones/pcl,closerbibi/pcl,KevenRing/pcl,KevenRing/pcl,mikhail-matrosov/pcl,mschoeler/pcl,KevenRing/pcl,pkuhto/pcl,ResByte/pcl,srbhprajapati/pcl,zavataafnan/pcl-truck,starius/pcl,nikste/pcl,ipa-rmb/pcl,stfuchs/pcl,cascheberg/pcl,Tabjones/pcl,KevenRing/vlp,ipa-rmb/pcl,shangwuhencc/pcl,lebronzhang/pcl,jeppewalther/kinfu_segmentation,wgapl/pcl,ipa-rmb/pcl,stefanbuettner/pcl,stfuchs/pcl,pkuhto/pcl,the-glu/pcl,v4hn/pcl,ipa-rmb/pcl,stfuchs/pcl,krips89/pcl_newfeatures,soulsheng/pcl,simonleonard/pcl,msalvato/pcl_kinfu_highres,shivmalhotra/pcl,v4hn/pcl,zhangxaochen/pcl,shivmalhotra/pcl,3dtof/pcl,shangwuhencc/pcl,mschoeler/pcl,jakobwilm/pcl,shangwuhencc/pcl,kanster/pcl,msalvato/pcl_kinfu_highres,3dtof/pcl,lebronzhang/pcl,pkuhto/pcl,KevenRing/vlp,Tabjones/pcl,nh2/pcl,krips89/pcl_newfeatures,shivmalhotra/pcl,MMiknis/pcl,chatchavan/pcl,damienjadeduff/pcl,chatchavan/pcl,drmateo/pcl,shyamalschandra/pcl,KevenRing/pcl,krips89/pcl_newfeatures,drmateo/pcl,mschoeler/pcl,chenxingzhe/pcl,shyamalschandra/pcl,jeppewalther/kinfu_segmentation,3dtof/pcl,mikhail-matrosov/pcl,stefanbuettner/pcl,closerbibi/pcl,krips89/pcl_newfeatures,cascheberg/pcl,ResByte/pcl,chenxingzhe/pcl,sbec/pcl,mschoeler/pcl,wgapl/pcl,zhangxaochen/pcl,kanster/pcl,jeppewalther/kinfu_segmentation,srbhprajapati/pcl,chenxingzhe/pcl,sbec/pcl,stefanbuettner/pcl,LZRS/pcl,zhangxaochen/pcl,lydhr/pcl,raydtang/pcl,starius/pcl,fskuka/pcl,lydhr/pcl,soulsheng/pcl,fskuka/pcl,msalvato/pcl_kinfu_highres,KevenRing/vlp,zavataafnan/pcl-truck,zavataafnan/pcl-truck,starius/pcl,nh2/pcl,shyamalschandra/pcl,ipa-rmb/pcl,nikste/pcl,locnx1984/pcl,shangwuhencc/pcl,locnx1984/pcl,simonleonard/pcl,stfuchs/pcl,fanxiaochen/mypcltest,mikhail-matrosov/pcl,damienjadeduff/pcl,soulsheng/pcl,lydhr/pcl,zhangxaochen/pcl,cascheberg/pcl,wgapl/pcl,nh2/pcl,lydhr/pcl,chatchavan/pcl